California's chief librarian is giving San Diego until July to move forward on a $185 million downtown central library and school, but she wants to see the money from private donors who have kept the project alive for years.

Susan Hildreth, the outgoing state librarian, said she is “concerned” about the “viability” of local funds.

In response to San Diego's request to keep a $20 million state grant – even though city officials missed the Dec. 31 deadline to move forward – Hildreth is demanding to see proof of the reported $33 million in private pledges.

“Please provide donor agreement letters or similar documents that verify the availability of the $33 million in private contributions as mentioned,” she wrote to the city in a letter Wednesday.

The library, estimated in 2005 to cost $185 million, is short on funds because private donations have fallen below expectations.

The city and its school district are still trying to figure out who will pay for a $168,000 feasibility study to determine whether a new high school school can be graphed onto the long-standing library blueprints in order to use $15 million to $20 million in school bond money to fill the funding gap.

The school-library concept surfaced late last year, just as the state grant was set to expire. The plan is to use money from November's Proposition S that was earmarked for a new downtown school.

A nonprofit foundation has raised $33 million toward the $85 million goal for private funds, including $1 million from the Hervey Family Foundation and $2 million from David Copley, chairman and CEO of The Copley Press Inc. and publisher of The San Diego Union-Tribune.

The rest of the money would come from $80 million in redevelopment tax dollars, plus the $20 million state grant.